我想更有效地实现这一目标而优雅从select语句在SQL
SELECT
MD.*,
(SELECT City FROM PostcodeData WHERE MD.Postcode = Postcode) [City],
(SELECT State FROM PostcodeData WHERE MD.Postcode = Postcode) [State],
(SELECT Areacode FROM PostcodeData WHERE MD.Postcode = Postcode) [Areacode]
FROM MemberDetails AS MD
我能明显INNER JOIN ON邮编两个表,但我有问题时,MemberDetail.postcode确实拉动多个值不存在于PostcodeData.postcode中。在这种情况下,我仍然希望选择这些成员,但对于城市,州和Areacode的结果为NULL。这在当前查询中已经实现,但效率很低。任何想法,将不胜感激。干杯!
干杯@sgegges,左加入是我之后 – Gregology 2013-02-22 20:08:55